Intraocular lenses have been increasingly used in the last decade, in particular in aphakic patients after a cataract operation. Intraocular lenses provide many advantages over both spectacle and contact lenses. They permit a better elimination of perceptual problems and reduce image size disparity. Since the intraocular lens is intended to remain in situ, it eradicates the difficulties in inserting and removing contact lenses encountered by elderly patients. The use of an intraocular lens may also be advantageous for those working in unusual environments and for those whose visual requirements for occupation must be fulfilled. Presently, opthamologists and eye surgeons recommend that intraocular implant lens surgery be performed when the patient is not likely to manage a contact lens.
According to Norman S. Jaffe et al, "Pseudophakos", published by The C.V. Mosby Company, 1978, the majority of patients who undergo lens implant surgery in the United States receive implants whose power is estimated from the basic refraction of the eye. Experience has shown however that there are many pitfalls in estimating the basic refraction in this way, in view of the high incidence of residual anisometropia and aniseikonia cases in patients thus corrected. More recently ophthalmologists surgeons have endeavoured to design bifocal intraocular lenses (IOL hereinafter) to focus both the near and far images on the retina. The "Ocular Surgery News", June 1, 1987, Volume 5, Number 11, reports the latest findings concerning bifocal IOL's. These IOL's, however, provide near and distance vision but do not provide a continuum in the dioptric range. To the best of the inventor's knowledge, there is not known any multifocal intraocular lens.